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# Re: Big strings => panic

- Date: Fri, 19 Apr 1996 12:23:12 PDT
- From:
- cc: MOO-Cows <moo-cows@parc.xerox.com>
- Content-Type: TEXT/PLAIN; charset=US-ASCII
- In-Reply-To: <v01530501ad9d8dbd9403@[150.203.102.53]>

    On Fri, 19 Apr 1996, Matthew Sanderson wrote:

    > It seems MOO server 1.7.8p4 panics when a string gets extremely long (I'm
    > not sure exactly how long, but I would guess LONG long).

    > foo = " ";
    > while(1)
    >   foo = foo + foo;
    >   $command_utils:suspend_if_needed(0);
    > endwhile

    It's not a "bug" per se, nor is it something easily fixed.

    What happens is simply that when a variable (list or string) gets very
    large, the server runs out of memory.  (The process hits a process-memory
    limit, the memory manager is unable to allocate a contiguous block of
    memory large enough, in extreme cases the swap space is exhausted.)  When
    the server runs out of memory, it panics -- and in this case probably
    produces one *very large* panic dump.

    The MOO execution unit does not impose any limits on how much memory a
    task can use: how big variables can get or how many there can be.
    Therefore, there's no way for the server to tell when this is about to
    happen.  (And, Pavel's said previously that there's no easy way to make
    the server impose limits on task size.)

      --Chris                           cunkel@engin.umich.edu
        ResComp Network Support Technician, Bursley Hall
        "Invisibility is in the eye of the beholder."
        Home Page: http://www-personal.engin.umich.edu/~cunkel/

Follow-Ups:

- Re: Big strings => panic

- From: tom@mvision.com (Tom Ritchford)

References:

- Big strings => panic

- From: m.sanderson@student.anu.edu.au (Matthew Sanderson)

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